1. Field of the Invention
This invention relates to a housing assembly for an electrical switching apparatus and, more specifically, to an extension rail assembly for an electrical switching apparatus housing assembly.
2. Background Information
An electrical switching apparatus is typically disposed in a housing assembly. The housing assembly is, typically, a rectangular box having a back sidewall, a top sidewall, a bottom sidewall, a right sidewall, a left sidewall, and a front sidewall. Selected sidewalls, typically the back sidewall or the top and bottom sidewalls, have openings therethrough which are structured to accommodate the line and load conductors for the electrical switching apparatus. The front sidewall may be movable, or removable, so as to allow access to the enclosed space defined by the housing assembly. An electrical switching apparatus may be disposed in the enclosed space defined by the housing assembly and coupled to the line and load conductors.
Certain types of electrical switching apparatus have a considerable weight. Further, certain types of electrical switching apparatus, such as, but not limited to, a circuit breaker having a high interruption capability, are known to experience high loads during operation. These loads are transferred to the housing assembly. To support the electrical switching apparatus and to assist in transferring loads from the electrical switching apparatus to the housing assembly, a typical housing assembly includes a pair of support rails. That is, a typical electrical switching apparatus includes a plurality of wheels structured to travel over, or within, a defined track. The track is often a pair of generally parallel support rails.
Support rails for an electrical switching apparatus housing assembly may be disposed upon the bottom sidewall or on a frame assembly disposed within the housing assembly but, preferably, the support rails are coupled to the right and left sidewalls. Such rails are typically coupled to the sidewalls by a plurality of fasteners such as, but not limited to, nuts and bolts or by a coupling method such as welding. The support rails typically include a thin metal plate that is oriented with a thin edge disposed as the uppermost surface. The electrical switching apparatus plurality of wheels are structured to travel over the support rail uppermost surface.
The support rails are structured to support the electrical switching apparatus within the housing assembly. Many electrical switching apparatus housing assemblies also include a pair of rail extensions that may be extended from the housing assembly. The rail extensions are aligned with the support rails and allow the electrical switching apparatus to be pulled from the housing assembly. That is, the rail extensions are also thin metal plates that are oriented with a thin edge disposed as the uppermost surface. A rail extension is disposed immediately in front of a support rail and aligned therewith. In this configuration, the electrical switching apparatus may be rolled from the support rails onto the rail extensions which are disposed, generally, outside of the housing assembly. Thus, the electrical switching apparatus is supported outside of the housing assembly and may have maintenance performed thereon, or, if the electrical switching apparatus is being replaced, the electrical switching apparatus may be transferred from the rail extensions to a cart or similar device for transportation.
Rail extensions may be incorporated into the housing assembly support rail assembly, may be separate components, or may be incorporated into a cart or other transportation device. While not incorporating rail extensions into each housing assembly does reduce the cost of a housing assembly, this configuration may result in the rail extension not being available when needed. Thus, having rail extensions incorporated into each housing assembly support rail assembly has advantages. However, present support rail/rail extension assemblies have several disadvantages.
For example, as noted above, support rails are typically coupled to the housing assembly by a plurality of fasteners or other more permanent coupling means. Such coupling structures are not efficient for transferring loads from the electrical switching apparatus to the housing assembly and, typically, require the use of additional support plates. Further, present support rail/rail extension assemblies are generally a grouping of separate components. That is, there is a support rail assembly within the housing assembly and a mounting disposed adjacent thereto. The rail extensions are coupled to the mounting. Each of these components is separately installed. Such components are typically coupled to the housing assembly and include various latches and releases, many with spring loaded elements, structured to maintain the extended rails in the storage configuration and/or the use configuration. Such mechanisms are difficult to actuate when users are wearing protective gloves.
Further, the housing assembly typically includes various features or components which must each be individually installed and maintained. For example, a housing assembly may include a separate alignment device structured to align the electrical switching apparatus terminals with the housing assembly bus assembly, a separate interface for a levering in mechanism, and a separate lockout device. A levering in mechanism interface is typically a very rigid contact point to which the levering in mechanism is coupled to and applies forces against. A lockout device is a safety device wherein a lock, such as, but not limited to, a padlock is locked to the housing assembly and thereby prevents the use of the electrical switching apparatus or the housing assembly. Such separate components could be incorporated into a single support rail assembly.
There is, therefore, a need for a support and extension rail assembly for an electrical switching apparatus housing assembly that provides a mounting for the extension rails.
There is a further need for a support and extension rail assembly for an electrical switching apparatus housing assembly that assists in the transfer of loads to the housing assembly.
There is a further need for a support and extension rail assembly for an electrical switching apparatus housing assembly that assist in the alignment of the primary and secondary bus terminals of the electrical switching apparatus.
There is a further need for a support and extension rail assembly for an electrical switching apparatus housing assembly that provides a levering in mechanism interface.
There is a further need for a support and extension rail assembly for an electrical switching apparatus housing assembly that incorporates a lockout device.
There is a further need for a support and extension rail assembly for an electrical switching apparatus housing assembly that incorporates a simplified latch.
There is a further need for a support and extension rail assembly for an electrical switching apparatus housing assembly that may be actuated by a user wearing protective equipment including, but not limited to, electrical gloves.